Cigarettes are a major cause of disease and excess mortality. Techniques that can assist smokers in quitting would have obvious health benefits. The proposed investigation examines clinic approaches to smoking sessation. It compares within the frame-work of a single focused study leading public service methods (American Cancer Society, American Lung Association) and a promising experimental procedure developed by the principal investigator. Intensive publicity will be devoted to the availability of help for smoking cessation in three target communities: Des Moines, Waterloo, and Cedar Rapids. Subjects will be assigned randomly to the American Lung Association, the American Cancer Society, or the Lando method. Key elements are hypothesized to include group support, target date for quitting, and specific preparation leading to the target date. On this basis, the order of outcome for clinics is predicted to be: Lando, American Lung Association, American Cancer Society. Detailed smoking history, demographic and environmental data will allow assessment of characteristics of smokers and of factors associated with the maintenance of nonsmoking. Replication in three communities will increase confidence in the generalizability of the results and will permit recruitment of an adequate subject pool to detect relatively small effects. Quantitative assessment of group cohesiveness will provide an important indication of level of support and of the relationship between level of support and outcome. This study is conceptualized as part of a comprehensive broad-spectrum approach to the problems of smoking prevention and cessation. Parental smoking models are one of the strongest determinants of adolescent uptake of the tobacco habit.